great idea, the diode would prevent any cross charging of cells.
with a HIGH load device an tiny bits of resistance due to the number of connections that exist you could indeed end up with a parellel imbalance.
usually the loads are so minimal that parellel imbalance is not an issue, but if your doing crasy drain a battery applications with hotwires, and the batteries are not Soldered or Tabbed, in with fat copper and all, it certannly could become an issue. even a holder spring can have more resistance than one would expect when used with high amperages.
it would depend a lot on the application, and when the application is some AA holder thing and a HOT incan bulb then it would be an application where it would be concidered.
a parellel imbalance wouldnt be a big issue with ni-??? but it would be with Primary cells that do not intend to be charged in any way shape or form, especially lithium primaries.
there are "shotkey" diodes that are 1/2 the voltage drop at about .3V drop, not only do they drop less, but BECAUSE they drop less there is less heat dissipation needed to keep the diode from overheating.
then there is a Trick you can do with a MOSFET, that has almost 0 resistance , you turn a mosfet into a diode by how you wire it, and it requires gate voltage to stay open. i dont quite understand how exactally, only did it once but its one way to have diode like protection with about .01-.001ohm resistance AS LONG AS you have the voltage for the gate, which could come in handy as a low volt cutoff, or terrible (also) as the mosfet became higher in resistance (heat).
if somone was whining about the waste or voltage losses, they could look into how to make a mosfet work like a diode in that particualr application (for that application because of the mosfets gate voltage)
